Method for comprehensive utilization of fluorogypsum and aluminum electrolyte

Abstract

The present application relates to a method for comprehensive utilization of fluorogypsum and aluminum electrolyte, and belongs to the technical field of metallurgical solid waste treatment. 2+ The reaction forms CaF2, which can be used again for preparation of HF, while other non-metal elements escape in the form of tail gas. The aluminum element and lithium element in the aluminum electrolyte waste residue powder are dissolved in the alkali solution after phase conversion by roasting, so as to realize separation from other impurity ions. Pure lithium ion solution and aluminate solution are obtained through subsequent alkali lithium extraction process and impurity ion purification process, which can be used for preparation of high-purity lithium salt and aluminum hydroxide. The roasting process of the method for comprehensive utilization of fluorogypsum and aluminum electrolyte does not produce corrosive HF, has low requirement on reaction equipment, is safe and reliable, and is conducive to cost control.

Description

TECHNICAL FIELD

[0001] The application relates to a method for comprehensively utilizing fluorogypsum and aluminum electrolyte, and belongs to the technical field of metallurgical solid waste treatment. BACKGROUND

[0002] Fluorogypsum is an industrial waste produced in the preparation of HF by the fluorite method, and contains more than 90% of CaSO4 and a small amount of impurities such as CaF2 and CaO. Newly discharged fluorogypsum has a certain acidity due to the presence of residual H2SO4 and HF. In theory, 1t of hydrogen fluoride can produce 3.6t of fluorogypsum, so the annual fluorogypsum discharge in China is more than one million tons. The main component of fluorogypsum is type II anhydrous gypsum which is difficult to hydrate and has low early strength, and therefore cannot be directly used in the construction industry. At present, when fluorogypsum is treated, it is only simply neutralized and then stored or landfilled, which not only causes great resource waste, but also has a serious negative impact on environmental protection.

[0003] In addition to modifying fluorogypsum for use as a building material, researchers have also made some research on using recycled fluorogypsum as an industrial raw material. Chinese patent document CN106365476A discloses a method for preparing a sulphoaluminate cement and co-producing sulfuric acid from desulfurized gypsum, which uses desulfurized gypsum, bauxite, silica and anthracite as raw materials, and the tail gas SO2 is used for acid production process. This method uses desulfurized gypsum as the main material, and needs to consume a large amount of natural materials such as lime, bauxite and silica, and the calcination temperature is as high as 1250-1300℃, which has high energy consumption. Chinese patent document CN101486481A discloses a method for preparing superfine light calcium carbonate and co-producing ammonium sulfate by reacting fluorogypsum, ammonia water, surfactant and ammonium bicarbonate in a solution, in which fluorogypsum is converted into superfine light calcium carbonate and ammonium sulfate with certain economic value, but the economic benefit of this method is not high, and the conversion and utilization of fluorogypsum is limited.

[0004] Aluminum electrolyte is a reaction medium for dissolving alumina and electrolyzing into metallic aluminum in the aluminum electrolysis process, which is composed of cryolite (Na3AlF6) and other fluoride salt additives such as AlF3, CaF2, MgF2, LiF and CaO. However, with the continuous production, the enrichment of lithium salt will lead to the decrease of alumina solubility, affecting the efficiency of aluminum electrolysis. In order to maintain the balance of electrolyte in the aluminum electrolysis tank, it is necessary to regularly take out the excess aluminum electrolyte for storage, which causes great resource waste. It is of great significance to recover valuable elements in aluminum electrolyte waste, especially lithium resources.

[0005] The roasting-leaching method is a common method for recycling aluminum electrolyte at present. The addition of phase transfer agent in roasting can convert the insoluble salts such as lithium sodium cryolite in aluminum electrolyte into soluble or easily leached salts, which is beneficial to the gradient recovery of valuable elements. The phase transfer agents used in the roasting process at present include aluminum salt (CN114853042A), fluoride (CN105543504A), alkali or basic oxide (CN115216630A, CN113684369A, CN110284157A, CN115216645A) and acid salt (CN105925819A) and the like. The patent document CN110284157A discloses a recycling method, which comprises the following steps: mixing and roasting aluminum electrolysis anode residue with calcium-containing substances (lime, limestone, calcium hydroxide) and alkali-containing substances (sodium carbonate, sodium bicarbonate, sodium hydroxide) at a high temperature of 700-1400 DEG C, and then obtaining calcium fluoride and sodium aluminate and caustic soda solution through alkali leaching treatment of the roasting product, and then returning to the Bayer process of aluminum production process. However, the method is roasting in a strong alkali environment, and the recovery rate of lithium element is not higher than 75%.

[0006] In summary, in order to reduce the cost of raw materials and environmental protection, it is urgent to develop a method for comprehensive utilization of fluorogypsum and aluminum electrolyte, so as to achieve the purpose of treating fluorogypsum and extracting valuable elements (lithium element) in aluminum electrolyte at the same time, thereby solving the problems of limited conversion and utilization of fluorogypsum and low recovery rate of lithium element in extracting lithium element from aluminum electrolyte. SUMMARY

[0007] The purpose of the present application is to provide a method for comprehensive utilization of fluorogypsum and aluminum electrolyte, which can solve the problems of limited conversion and utilization of fluorogypsum and low recovery rate of lithium element in extracting lithium element from aluminum electrolyte.

[0008] In order to achieve the above purpose, the technical scheme adopted by the method for comprehensive utilization of fluorogypsum and aluminum electrolyte of the present application is as follows:

[0009] A method for comprehensive utilization of fluorogypsum and aluminum electrolyte, comprising the following steps:

[0010] (1) roasting a mixture mainly composed of aluminum electrolyte residue powder, fluorogypsum and roasting agent, wherein the roasting agent is ammonium carbonate and / or ammonium bicarbonate;

[0011] (2) alkali leaching the solid roasting product obtained in step (1) with alkali solution, solid-liquid separation, adsorbing lithium ions in the liquid obtained by solid-liquid separation with adsorbent, then eluting the adsorbent after adsorption treatment to obtain a lithium ion solution, and mixing the liquid after adsorption treatment with hydrogen peroxide to prepare an aluminate solution.

[0012] The method for comprehensive utilization of fluorogypsum and aluminum electrolyte of the present application first roasts a mixture mainly composed of aluminum electrolyte waste residue powder, fluorogypsum and a roasting agent, and the fluorine element in the aluminum electrolyte waste residue powder reacts with the Ca 2+ to form CaF2, which can be used again to prepare HF, while other non-metal elements escape in the form of tail gas. The aluminum element and lithium element in the aluminum electrolyte waste residue powder are dissolved in the alkali liquor after phase conversion by roasting, realizing separation from other impurity ions, and a pure lithium ion solution and an aluminate solution are obtained by subsequent alkali liquor lithium extraction process and impurity ion purification process, which can be used to prepare high-purity lithium salt and aluminum hydroxide. In addition, the roasting process of the method for comprehensive utilization of fluorogypsum and aluminum electrolyte of the present application does not produce corrosive HF, and the requirement for the reaction equipment is not high, and it is safe and reliable; and the main material used in the method for comprehensive utilization of fluorogypsum and aluminum electrolyte of the present application is solid waste fluorogypsum and waste aluminum slag, which is conducive to cost control.

[0013] The method for comprehensive utilization of fluorogypsum and aluminum electrolyte of the present application utilizes a roasting agent as a modifier of the fluorogypsum-aluminum electrolyte mixed roasting recovery process from the aspects of reducing raw material cost and environmental protection, and then valuable elements in the fluorogypsum and aluminum electrolyte are extracted through leaching process, lithium extraction process and purification process, realizing collaborative resource utilization of the two kinds of solid waste.

[0014] It can be understood that the lithium ion solution prepared in step (2) can be used to produce battery-grade lithium salt after concentration.

[0015] It can be understood that the aluminum electrolyte waste residue powder contains lithium elements.

[0016] In order to ensure that the mixture is fully mixed and roasted, preferably, the particle size of the aluminum electrolyte waste residue powder is not less than 50 mesh. Further, the particle size of the aluminum electrolyte waste residue powder is not less than 200 mesh.

[0017] In order to improve the roasting effect, preferably, the average particle size of the mixture is less than 30 μm.

[0018] Preferably, the molar ratio of fluorine ions, calcium ions and carbonate ions in the mixture is (1.5-2):(1-1.2):(1.2-1.5). The fluorine ions are F - , the calcium ions are Ca 2+ , and the carbonate ions are CO3 2- .

[0019] During the roasting process, the calcium sulfate in the fluorogypsum reacts with the roasting agent to obtain calcium carbonate and ammonium sulfate, and the ammonium sulfate is further heated and decomposed to obtain ammonia, nitrogen, sulfur dioxide and water vapor. At the same time, the calcium carbonate is heated and decomposed to obtain calcium oxide and carbon dioxide, and the calcium oxide in the fluorogypsum, the calcium oxide generated by the heating and decomposition of the calcium carbonate, and the calcium oxide in the aluminum electrolyte react with cryolite, AlF3 and LiF in the aluminum electrolyte residue powder to generate corresponding oxides and calcium fluoride. When the roasting agent is ammonium carbonate, the specific chemical reactions are as follows:

[0020] CaSO4+ (NH4)2CO3→ (NH4)2SO4+ CaCO3

[0021] 3 (NH4)2SO4= 4NH3↑+ N2↑+ 3SO2↑+ 6H2O↑

[0022] CaCO3= CaO+ CO2↑

[0023] 3CaO+ 2AlF3→ Al2O3+ 3CaF2

[0024] CaO+ 2LiF→ Li2O+ CaF2

[0025] 3CaO+ Na3AlF6→ NaAlO2+ Na2O+ 3CaF2.

[0026] The roasting is to make the calcium sulfate in the fluorogypsum react with the roasting agent, and to make the obtained calcium carbonate and ammonium sulfate further heated and decomposed, and to make the calcium oxide and cryolite, AlF3 and LiF react to generate corresponding oxides and calcium fluoride. Therefore, the roasting temperature and the roasting time can be determined according to the temperature required by the above reactions. Preferably, the temperature of the roasting is 750°C to 900°C. For example, the temperature of the roasting is 800°C. The conversion of the residue can also be achieved at a higher roasting temperature, but the high temperature resistance requirement of the equipment is high and the energy consumption is large, so it is not preferred.

[0027] Preferably, the time of the roasting is 1 to 2 hours. For example, the time of the roasting is 2 hours.

[0028] In order to avoid environmental pollution and make full use of resources, preferably, the waste gas generated by the roasting is absorbed by dilute ammonia water. After the waste gas generated by the roasting is absorbed by the dilute ammonia water, air is then introduced to obtain an ammonium sulfate solution, which can be used as a fertilizer raw material.

[0029] It can be understood that, in step (2), when the solid roasting product obtained in step (1) is subjected to alkali leaching with lye, the chemical reaction that occurs is: Al2O3+ 2OH - = 2AlO2 -+ H2O; Li2O + H2O = 2LiOH; Na2O + H2O = 2NaOH. When the basic compound in the lye is sodium hydroxide, the system after the alkaline leaching contains CaF2 solid and a solution containing sodium ions, lithium ions and meta-aluminate ions.

[0030] Preferably, in step (2), the mass ratio of the solid roasting product to the lye is 1: (5-10).

[0031] Preferably, in step (2), the temperature for the alkaline leaching is 20-90°C. For example, in step (2), the temperature for the alkaline leaching is 60°C.

[0032] The purpose of the alkaline leaching is to make the alumina react with the lye to form aluminate, thus the pH and the amount of the lye can be determined according to whether the alumina can be completely reacted. Preferably, in step (2), the pH of the lye is 10-12.

[0033] Preferably, in step (2), the lye mainly consists of water and a basic compound. In order to avoid introducing other impurities, preferably, the basic compound is sodium hydroxide and / or sodium carbonate.

[0034] It can be understood that, in step (2), the main component of the solid obtained by the solid-liquid separation is CaF2, and the regenerated fluorite is obtained after drying. In step (2), the main component of the liquid obtained by the solid-liquid separation is a solution containing sodium ions, lithium ions and meta-aluminate ions.

[0035] It can be understood that, when the lithium ions in the liquid obtained by the solid-liquid separation are treated by using the adsorbent, the adsorbent and the liquid obtained by the solid-liquid separation can be mixed, and then the solid-liquid separation is performed, the liquid obtained by the solid-liquid separation is the liquid after the adsorption treatment, and the solid obtained by the solid-liquid separation is the adsorbent after the adsorption treatment; or the liquid obtained by the solid-liquid separation is passed through an adsorption column containing the adsorbent, and the adsorbent after the adsorption of the lithium ions is the adsorbent after the adsorption treatment, and the liquid after passing through the adsorption column is the liquid after the adsorption treatment.

[0036] Preferably, in step (2), the adsorbent is an ion sieve type adsorbent. Further, in step (2), the ion sieve type adsorbent is a manganese ion sieve.

[0037] Preferably, in step (2), the eluent used for the elution is water or an inorganic acid. Preferably, the inorganic acid is dilute sulfuric acid. Preferably, the mass fraction of the dilute sulfuric acid is 5-30%. For example, the mass fraction of the dilute sulfuric acid is 10%.

[0038] Preferably, in step (2), after the liquid after the adsorption treatment is mixed with hydrogen peroxide and then the solid-liquid separation is performed, the liquid obtained by the solid-liquid separation is the sodium aluminate solution.

[0039] It can be understood that in step (2), the main component of the liquid after the adsorption treatment is a solution containing sodium ions, manganese ions and metavanadate ions, and after mixing with hydrogen peroxide, solid precipitate and sodium aluminate solution are obtained, and the main component of the solid precipitate is MnO(OH) and MnO2. The chemical reaction is: Mn 2+ + H2O2 + OH - = MnO(OH)↓ + H2O, Mn 2+ + H2O2 + 2OH - = MnO2↓ + 2H2O.

[0040] Preferably, in step (2), the mass fraction of the hydrogen peroxide is 30-90%. The amount of hydrogen peroxide can be determined according to the amount of manganese ions in the liquid after the adsorption treatment. In step (2), the ratio of the molar amount of hydrogen peroxide in the hydrogen peroxide to the molar amount of manganese ions in the liquid after the adsorption treatment is (1.05-1.2):1. A slight excess of hydrogen peroxide can make the manganese ions precipitate completely, and the excess hydrogen peroxide will be decomposed into water and oxygen in the lye, without introducing impurities.

[0041] After the sodium aluminate solution is prepared, in order to further recycle and utilize aluminum resources and sodium resources, preferably, the method for comprehensively utilizing fluorogypsum and aluminum electrolyte further comprises the following steps: mixing the sodium aluminate solution with carbon dioxide, solid-liquid separation, and the solid obtained by the solid-liquid separation is aluminum hydroxide, and then the liquid obtained by the solid-liquid separation is concentrated and crystallized to obtain sodium carbonate. After the sodium carbonate is prepared, the sodium carbonate can be used to prepare lye for alkaline leaching or mixed with a lithium ion solution to prepare lithium carbonate. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a process flow diagram of the method for comprehensively utilizing fluorogypsum and aluminum electrolyte according to the embodiments of the present application. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0044] Embodiment 1

[0045] The method for comprehensively utilizing fluorogypsum and aluminum electrolyte according to the present embodiment, as shown in Figure 1 , specifically comprises the following steps:

[0046] (1) Obtain fluorogypsum waste slag from a certain HF production plant, and the mass fraction of CaSO4 in the fluorogypsum waste slag is 94%, the mass fraction of CaF2 is 2-3%, and the mass fraction of CaO is 1-2%;

[0047] The waste aluminum electrolyte of an aluminum electrolysis plant is obtained, the waste aluminum electrolyte is crushed and sieved, and 50-mesh aluminum electrolyte waste residue powder is obtained, the mass fraction of Al 3+ in the aluminum electrolyte waste residue powder is 14% to 20%, the mass fraction of Na + is 20% to 30%, the mass fraction of F - is 40% to 50%, the mass fraction of Li + is 1% to 3%, and the mass fraction of CaO is 4% to 6%;

[0048] (2) 100 g of the aluminum electrolyte waste residue powder, 200 g of fluorogypsum, and 175 g of ammonium carbonate are uniformly mixed, and are ground for 2 h by using a micropowder mill to obtain a mixture with an average particle size of less than 30 μm, and the molar ratio of fluorine ions, calcium ions, and carbonate ions in the mixture is (1.5 to 2) : (1.1 to 1.2) : 1.3;

[0049] (3) the mixture obtained in step (2) is mixed and calcined at 800°C for 2 h to obtain 173 g of a solid calcination product; at the same time, the tail gas generated in the calcination is absorbed by using dilute ammonia water, and air is introduced into the obtained liquid to obtain an ammonium sulfate solution;

[0050] (4) the solid calcination product obtained in step (3) is uniformly mixed with 1 L of lye (the lye is prepared by mixing water and sodium hydroxide, and has a pH of 11), and is subjected to alkali leaching at 60°C for 2 h; since the solid calcination product contains lithium oxide and sodium oxide, the pH of the lye will increase after the lye is added, but the pH of the lye will decrease as the reaction between the hydroxide in the lye and the aluminum oxide proceeds; in order to ensure that the aluminum oxide is completely converted into metaborate, when the pH of the system is less than 12, lye is added to the system to control the pH of the system to be 12 to 13; after the alkali leaching is completed, the system after the alkali leaching, which has a pH of 12 to 13, is filtered to obtain filter residue A and filter liquor A; the filter residue A is calcined to obtain 110 g of regenerated fluorite, and the CaF2 content in the regenerated fluorite is 94%, and the regenerated fluorite also contains a small amount of MgF2 and CaO·SiO2 impurities;

[0051] (5) the filter liquor A is subjected to dynamic adsorption of lithium in the filter liquor A by using an adsorption column filled with an excess amount of manganese ion exchange resin at room temperature; after the adsorption is completed, the manganese ion exchange resin after the adsorption of lithium is washed with pure water, and then is eluted with dilute sulfuric acid with a mass fraction of 10%, and the eluate is a lithium ion solution;

[0052] Meanwhile, 10 mL of 90% hydrogen peroxide (the ratio of the molar amount of hydrogen peroxide in the hydrogen peroxide to the molar amount of manganese ions in the adsorption-treated liquid is 1.2:1) is added to the filtrate A (lithium extraction mother liquor) after adsorption treatment, and stirred for 30 min, and then filtered. The solid obtained by filtration is insoluble impurities, and the liquid obtained by filtration is a sodium aluminate solution (the content of other impurities in the sodium aluminate solution, except water and sodium aluminate, is less than 1%, and the recovery rate of aluminum element is 92%); in order to further recycle aluminum resources and sodium resources, carbon dioxide is introduced into the sodium aluminate solution to react with sodium aluminate and carbon dioxide to generate aluminum hydroxide and sodium carbonate. After the reaction is completed, filtration is performed to obtain 50.7 g of aluminum hydroxide solid. The liquid obtained by filtration is concentrated and crystallized to obtain sodium carbonate; after the sodium carbonate is prepared, the sodium carbonate can be used to prepare lye for alkali leaching or mixed with a lithium ion solution to prepare lithium carbonate;

[0053] (6) The lithium ion solution prepared in step (5) is heated and concentrated, and after cooling, a concentrated solution (the mass fraction of lithium element in the concentrated solution is 20%) is obtained. Then 20 g of sodium carbonate is added to the concentrated solution, and stirred at 20°C until no precipitate is generated. Then filtration is performed. The solid obtained by filtration is dried to obtain 13.7 g of lithium carbonate product (purity is 99.68%), that is, the total mass of recovered lithium element is 2.6 g.

[0054] Example 2

[0055] The method for comprehensive utilization of fluorogypsum and aluminum electrolyte in the embodiment specifically includes the following steps:

[0056] (1) 560 g of aluminum electrolyte waste residue powder, 1000 g of fluorogypsum, and 890 g of ammonium carbonate are uniformly mixed, ground for 2 h by a micro-powder mill to obtain a mixture with an average particle size of less than 30 μm, and the molar ratio of fluorine ions, calcium ions, and carbonate ions in the mixture is (1.6-2):1:1.2; the aluminum electrolyte waste residue powder and the fluorogypsum used in the method for comprehensive utilization of fluorogypsum and aluminum electrolyte in the embodiment are the same as the aluminum electrolyte waste residue powder and the fluorogypsum used in the method for comprehensive utilization of fluorogypsum and aluminum electrolyte in Example 1;

[0057] (2) The mixture obtained in step (2) is mixed and calcined at 750°C for 2 h to obtain 945 g of a solid calcination product; meanwhile, dilute ammonia water is used to absorb the tail gas generated by calcination, and air is introduced into the liquid obtained by absorption to obtain an ammonium sulfate solution;

[0058] (3) the solid roasting product obtained in step (3) is mixed with 6 L of alkali liquor (the alkali liquor is prepared by mixing water and sodium hydroxide, and the pH is 10), and is subjected to alkali leaching at 20°C for 2 h. After the alkali liquor is added, the pH of the alkali liquor increases due to the presence of lithium oxide and sodium oxide in the solid roasting product, but the pH of the alkali liquor decreases as the reaction between the hydroxide in the alkali liquor and the aluminum oxide proceeds. In order to ensure that the aluminum oxide is completely converted into metaborate, when the pH of the system is less than 12, the alkali liquor is added to the system to control the pH of the system at 12-13. After the alkali leaching is completed, the alkali leached system with a pH of 12-13 is filtered to obtain filter residue A and filter liquor A. The filter residue A is calcined to obtain 576 g of regenerated fluorite, and the CaF2 content in the regenerated fluorite is 96% by determination;

[0059] (4) the filter liquor A is subjected to dynamic adsorption of lithium in the filter liquor A by using an adsorption column filled with excess manganese ion exchange resin at room temperature. After the adsorption is completed, the manganese ion exchange resin after adsorbing lithium is washed with pure water, and then is eluted with 10% dilute sulfuric acid. The eluate is a lithium ion solution;

[0060] Meanwhile, 150 mL of 30% hydrogen peroxide solution (the ratio of the molar amount of hydrogen peroxide in the hydrogen peroxide solution to the molar amount of manganese ions in the adsorption-treated liquid is 1.05:1) is added to the adsorption-treated filter liquor A (lithium extraction mother liquor), and is stirred for 30 min. Then, filtration is performed. The solid obtained by filtration is insoluble impurities, and the liquid obtained by filtration is a sodium aluminate solution (the content of other impurities in the sodium aluminate solution is less than 1% in addition to water and sodium aluminate, and the recovery rate of aluminum element is 85%);

[0061] (5) the lithium ion solution prepared in step (4) is heated and concentrated, and after cooling, a concentrated solution (the mass fraction of lithium element in the concentrated solution is 20%) is obtained. Then, 20 g of sodium carbonate is added to the concentrated solution, and is stirred at 20°C until no precipitate is generated. Then, filtration is performed. The solid obtained by filtration is dried to obtain 82.3 g of lithium carbonate product (the purity is 99.73%), and the total mass of the recovered lithium element is 15.5 g.

[0062] Example 3

[0063] The method for comprehensively utilizing fluorogypsum and aluminum electrolyte in the embodiment specifically includes the following steps:

[0064] (1) 1000 g of aluminum electrolyte residue powder, 2200 g of fluorgypsum and 2000 g of ammonium carbonate were mixed uniformly, and ground for 2 h using a micro-powder mill to obtain a mixture with an average particle size of less than 30 μm, and the molar ratio of fluorine ions, calcium ions and carbonate ions in the mixture was (1.55-2): 1.2: 1.5; the aluminum electrolyte residue powder and the fluorgypsum used in the method for comprehensive utilization of fluorgypsum and aluminum electrolyte in the present example were the same as the aluminum electrolyte residue powder and the fluorgypsum used in the method for comprehensive utilization of fluorgypsum and aluminum electrolyte in Example 1;

[0065] (2) The mixture obtained in step (2) was mixed and calcined at 900°C for 1 h to obtain 1870 g of solid calcination product; at the same time, the tail gas generated during calcination was absorbed using dilute ammonia water to obtain an ammonium sulfate solution;

[0066] (3) The solid calcination product obtained in step (3) was mixed with 10 L of lye (the lye was prepared by mixing water and sodium hydroxide, and the pH was 12), and the mixture was subjected to alkali leaching at 20°C for 2 h. Since the solid calcination product contained lithium oxide and sodium oxide, the pH of the lye would increase after the lye was added, but the pH of the lye would decrease as the reaction between the hydroxide ions in the lye and the aluminum oxide proceeded. In order to ensure that the aluminum oxide was completely converted into metaborate, when the pH of the system was less than 12, lye was added to the system to control the pH of the system at 12-13. After the alkali leaching was completed, the system after alkali leaching was filtered to obtain filter residue A and filter liquor A. The filter residue A was calcined to obtain 1200 g of regenerated fluorite, and the CaF2 content in the regenerated fluorite was 90% as determined;

[0067] (4) The filter liquor A was subjected to dynamic adsorption of lithium in the filter liquor A using an adsorption column packed with excess manganese-based ion exchange resin at room temperature. After the adsorption was completed, the manganese-based ion exchange resin after adsorbing lithium was washed with pure water, and then eluted with dilute sulfuric acid with a mass fraction of 10% to obtain a lithium ion solution;

[0068] At the same time, 100 mL of hydrogen peroxide water with a mass fraction of 90% (the ratio of the molar amount of hydrogen peroxide in the hydrogen peroxide water to the molar amount of manganese ions in the liquid after adsorption treatment was 1.1:1) was added to the filter liquor A after adsorption treatment (lithium extraction mother liquor), stirred for 30 min, and then filtered. The solid obtained by filtration was insoluble impurities, and the liquid obtained by filtration was a sodium aluminate solution (the content of other impurities in the sodium aluminate solution, except water and sodium aluminate, was less than 1%, and the recovery rate of aluminum element was 94%);

[0069] (5) The lithium ion solution prepared in step (4) is heated and concentrated, and after cooling, a concentrated solution (the mass fraction of lithium element in the concentrated solution is 20%) is obtained. Then 20 g of sodium carbonate is added to the concentrated solution, and stirred at 20°C until no more precipitate is generated. Then filtration is performed, and the solid obtained by filtration is dried to obtain 153.3 g of lithium carbonate product (purity is 99.59%), i.e. the total mass of recovered lithium element is 28.8 g.

[0070] Experimental Example

[0071] The lithium carbonate product prepared in Examples 1-3 is detected by using the battery-grade lithium carbonate industry standard YS / T582-2013, and the composition and impurity content of the lithium carbonate are shown in Table 1.

[0072] Table 1 Composition and impurity content of lithium carbonate

[0073]

[0074] As shown in Table 1, the lithium carbonate prepared by using the method for comprehensive utilization of fluorogypsum and aluminum electrolyte according to the present application meets the industry standard of battery-grade lithium carbonate.

Claims

1. A method for comprehensive utilization of fluorgypsum and aluminum electrolyte, characterized in that, The method comprises the following steps: (1) roasting a mixture mainly composed of aluminum electrolyte residue powder, fluorogypsum and a roasting agent, the roasting agent being ammonium carbonate; the molar ratio of fluorine ions, calcium ions and carbonate ions in the mixture being (1.5-2):(1-1.2):(1.2-1.5); (2) subjecting the solid roasting product obtained in step (1) to alkali leaching with an alkali liquor, separating the solid and the liquid, subjecting the lithium ions in the liquid obtained after the solid-liquid separation to adsorption treatment with an adsorbent, then eluting the adsorbent after the adsorption treatment to obtain a lithium ion solution, and simultaneously subjecting the liquid after the adsorption treatment to a mixing reaction with hydrogen peroxide to prepare an aluminate solution.

2. The method for integrated utilization of fluorgypsum and aluminum electrolyte according to claim 1, characterized in that, The average particle size of the mixture is less than 30 μm.

3. The method for comprehensive utilization of fluorogypsum and aluminum electrolyte according to claim 1 or 2, characterized in that, The roasting temperature is 750-900 °C.

4. The method for comprehensive utilization of fluorgypsum and aluminum electrolyte according to claim 1 or 2, characterized in that, The roasting time is 1-2 h.

5. The method of integrated utilization of fluorgypsum and aluminum electrolyte according to claim 1, characterized in that, In step (2), the mass ratio of the solid roasting product to the alkali liquor is 1:(5-10); the alkali liquor is mainly composed of water and an alkaline compound; the alkaline compound is sodium hydroxide and / or sodium carbonate.

6. The method of integrated utilization of fluorgypsum and aluminum electrolyte according to any one of claims 1, 2 or 5, characterized in that, In step (2), the pH of the alkali liquor is 10-12.

7. The method of integrated utilization of fluorogypsum and aluminum electrolyte according to any one of claims 1, 2 or 5, characterized in that, In step (2), the temperature for the alkali leaching is 20-90 °C.

8. The method of integrated utilization of fluorgypsum and aluminum electrolyte according to any one of claims 1, 2 or 5, characterized in that, In step (2), the adsorbent is an ion sieve type adsorbent; the eluent for the elution is water or an inorganic acid.

9. The method of integrated utilization of fluorgypsum and aluminum electrolyte according to claim 8, characterized in that, In step (2), the ion sieve type adsorbent is a manganese-based ion sieve.

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